[Ivansgarage]

Slip is a speed difference. I suppose you could measure it as the speed at which maximum torque is developed with the rotor locked, but that would give an actual speed (in revolutions per minute or whatever), not a difference (slip is always 100% with the shaft not turning). I would expect it to be a fraction (percentage) of shaft speed in a running motor. What are the units of the value "1.33"? Is it 1.33% of shaft speed?

"What are the units of the value "1.33"? Is it 1.33% of shaft speed?"

really don't give a shit its what the the curtis controller needs to put out maximum torque.
We are not trying to design a new motor we are trying to get his controller set up.
I know what slip is it's the lag in the magnetic field (rotor lag)

LOOK it UP

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[brian_]

...
really don't give a shit its what the the curtis controller needs to put out maximum torque.
We are not trying to design a new motor we are trying to get his controller set up.
I know what slip is it's the lag in the magnetic field (rotor lag)

LOOK it UP

I suppose for someone who doesn't want to understand anything, this makes sense. It seems like it would have been easier to just answer the question (even just with "I don't know" or "I don't care") than compose this rant, but that's your choice.

The Curtis website claims to offer manuals, but only provides the datasheet, which does not answer the question, or list any setup parameters. It's a little difficult to look up.

In case anyone is interested... according to a post to a thread in Ivan's website, this value is the "slip gain" for an AC-50. It appears to be some response parameter, rather than the optimal slip.

 

[dcb]

Bri you seem to be ignoring the context here, and that ivan knows what he is doing. Besides slip as a % only makes sense at a fixed frequency. Slip gain (the only item in the curtis menu with slip in it) is much more useful.

 

[brian_]

It was just a question, and I do understand that "slip gain" makes more sense than "slip" as a controller tuning parameter. No need to get excited...

 

[Ivansgarage]

This is the big difference the SLIP gain has on the motor torque.

http://ivanbennett.com/forum/index.php?topic=17.msg1482#msg1482

Here is the numbers after the locked rotor test. The motor optimized at 7.00 on slip.
(torque is foot pounds)

slip -- torque -- amps
7.00 -- 142 -- 260
6.00 -- 160 -- 270
5.00 -- 180 -- 280
4.00 -- 220 -- 270
3.50 -- 225 -- 254

Looks like 3.50 is the best on slip gain. Had to turn brake pressure up all the way to hold it from turning.

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[[email protected]]

Thanks for the help. My plan at the moment is to get the car with the wheels off the ground on Saturday and run through the optimization procedure. Currently the settings I have puts the slip gain at 3.20. If I set this to 1.33 now will that cause a problem? I have left these values alone so far.

Also to optimize the motor etc., can I just put the gearbox in neutral? Save me having to jack the car up?

I need to check the values to run the optimization, but doe anybody have a recommendation about the rpm to run the procedure at? It seems I can choose, but don't know what to use.

I do have an extensive background in electronics and I have worked with some of the Siemens simovert drives for the dc motors used on industrial power presses. I have a good understanding. It has been many years since I worked in this area, but I do remember a fair amount. From my triaing and memory slip gain is like a ratio, so it has no units.

Shall I set the slip gain now before I optimize?

Thanks...

 

[Ivansgarage]

Thanks for the help. My plan at the moment is to get the car with the wheels off the ground on Saturday and run through the optimization procedure. Currently the settings I have puts the slip gain at 3.20. If I set this to 1.33 now will that cause a problem? I have left these values alone so far.

Also to optimize the motor etc., can I just put the gearbox in neutral? Save me having to jack the car up?

I need to check the values to run the optimization, but doe anybody have a recommendation about the rpm to run the procedure at? It seems I can choose, but don't know what to use.

I do have an extensive background in electronics and I have worked with some of the Siemens simovert drives for the dc motors used on industrial power presses. I have a good understanding. It has been many years since I worked in this area, but I do remember a fair amount. From my triaing and memory slip gain is like a ratio, so it has no units.

Shall I set the slip gain now before I optimize?

Thanks...

Yes just put it in neutral I would jack up the wheels just for safety sake.
do not worry about the slip you will change it after optimization.
Yes 1000 rpm is OK
You will get errors after optimization they allways come up don't worry about them. unless it does not optimize.

Optimizing Mizs motor.

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[[email protected]]

Today I ran the optimization procedure and it has worked. I can now pull away in second gear quite reasonably. I am just lazy, as 1st gear is a good solid pull. Got up to 90 on the main road, no controller overheat errors (no errors at all). I only got the expected parameter change error. I didn't jack the wheels off the ground and ran the procedure. When I went to pull awa, the drive was in reverse, so I ran it again with the throttle setting at -1 and then it was fine. The slip gain came back as 1.65 first time, then 1.75 second time. I remembered that this was not accurate so I tried to set this to 1.33, but the setting are to the nearest 0.05, so I set this to 1.35 as recommended for an HPEVS AC50 motor. Next job to rig up the tacho driver.

Thanks to everybody for your help. I am a happy zappy electric car driver again. Visit my site where I shall blog this challenge at:
http://www.probtron.blogspot.com